On July 4th, I went down to Oregon to install a crude sun-tracking solar panel system which I had designed and built.
I had not done the sun tracking angles exactly correct, and as it turned out, in the summer, the corners of the panel shade the sun-direction sensor.
So for summer time, I just moved the sensor to the top. Will have to move sensor to bottom for winter, or make new sensors that go on the right and left ends of the array.
The direction sensor is made from two little flexible solar panels connected in opposition of eachother (+ to - and - to +) and mounted inside a glass jar such that if one side gets more sun than the other, a positive voltage difference is created, or if the other side gets more sun, then a negative voltage is created. If the sun is equal on both halves, then the current from the two little flexible solar panels cancels eachother out.
The small voltage produced by the sun direction sensor goes to a pair of transistors which in turn control a pair of double throw single pole relays, which then run the motor one way or the other.
Because the flexible solar panels inside the jar wrap around almost 170 degrees each, it has around 170 degrees of operating range: That is to say that if the panel is aiming West where the sun set, and the sun rises in the east shining on the back of the array, the east-facing sensor half still picks it up and swings the array 170 degrees (or whatever) back to see the rising sun.
The solar panels are each rated at 100W with a max power at 18v and 5.56A, but since I don't have a Maximum Power Point Tracker yet, the panels run at battery voltage of 13.8v so I only get 76W from each panel, so for panels I get around 300W. The biggest power consuming device on this system is a small fridge, which averages 25W. (It uses 100W when running but only runs for 15 minutes out of the hour.)
Lord willing I'll be able to build a Maximum Power Point Tracker circuit to get more power as well as ultimately filling out the remaining 6 empty solar panel positions for a total of near a thousand watts.
The solar panels I used are from "Windy Nation" on ebay. They have the best deal I could find at the time of panels based on watts per dollar. When I got these four panels, they were $200 delivered. At the time of writing, they are down to around $180 or so delivered. As far as I can tell without waiting 15 years, they seem to be nice panels.
The 4 gauge red and black wire I used is real copper wire made in USA, also from ebay. I tried two brands but my favorite is SCOSCHE and it is very nice and easy to work with. It has very fine strands, each tin plated for corrosion resistance and easy soldering, and it has uv, water and oil resistant flexible insulation. Truly a pleasure to work with. It was only a dollar a foot delivered. Please note that most 4awg copper wire on ebay for a dollar a foot or less is actually copper plated aluminum - stay away from that! Aluminum has almost twice the resistance as copper, and is bad in so many ways.
The inverter is a Xantrex 1000W true sine inverter, rated at 800W continuous, 2000W surge. I chose a true sine inverter because the main purpose for this is a fridge - and induction motors really start and run better on a true sine.
This is a strictly off-grid system and it uses a 12v battery bank. It is all 12v except there is a small inverter to run a small fridge.